Three Polyhedron-Based Metal–Organic Frameworks Exhibiting Excellent Acetylene Selective Adsorption

The separation of acetylene (C 2 H 2 ) from ethylene (C 2 H 4 ) and ethane (C 2 H 6 ) is crucial for the production of high-purity C 2 H 2 and the recovery of other gases. Polyhedron-based metal–organic frameworks (PMOFs) are characterized by their spacious cavities, which facilitate gas trapping, and cage windows with varying sizes that enable gas screening. In this study, we carefully selected a class of PMOFs based on V-type tetracarboxylic acid linker ( JLU-Liu22 containing benzene ring, JLU-Liu46 containing urea group and recombinant reconstructed In/Cu CBDA on the basis of JLU-Liu46 ) to study the relationship between pore environment and C 2 adsorption and separation performance. Among the three compounds, JLU-Liu46 exhibits superior selectivity toward C 2 H 2 /C 2 H 4 (2.06) as well as C 2 H 2 /C 2 H 6 (2.43). Comparative structural analysis reveals that the exceptional adsorbed-C 2 H 2 performance of JLU-Liu46 can be attributed to the synergistic effects arising from coordinatively unsaturated Cu sites combined with an optimal pore environment (matched pore size and polarity, urea functional group), resulting in a strong affinity between the framework and C 2 H 2 molecules. Furthermore, transient breakthrough simulations of JLU-Liu46 confirmed its potential for separating C 2 H 2 in ternary C 2 gas.